Physics Commons^™

Can Newton’S Third Law Be “Derived” From The Second?, Asim Gangopadhyaya, James T. Harrington

Physics: Faculty Publications and Other Works

Newton’s laws1 have engendered much discussion over several centuries.2,3 Today, the internet is awash with a plethora of information on this topic. We find many references to Newton’s laws, often discussions of various types of misunderstandings and ways to explain them. Here we present an intriguing example that shows an assumption hidden in Newton’s third law that is often overlooked. As is well known, the first law defines an inertial frame of reference and the second law determines the acceleration of a particle in such a frame due to an external force. The third law describes forces exerted …